This invention relates generally to a method for manufacturing plastic floor mats for vehicles. More specifically, the invention relates to a method for manufacturing plastic floor mats molded to correspond with the three dimensional profile of the interior of a vehicle floor and having a plurality of integrally molded nibs on the surface of the mats to contact the vehicle's floor covering.
Mats are often placed over the floor board of a vehicle to protect the floor covering. Particularly, mats are useful to prevent the carpet or other floor covering from becoming worn, stained or otherwise damaged by the occupants of the vehicle or items stored within the vehicle.
Protective vehicle mats come in a variety of shapes and sizes. One typical prior art mat is a mat constructed from a flat sheet made of fabric, rubber or plastic material. The mats are typically flexible and are laid across the floor board surface of the vehicle. One drawback of these type of mats is that they tend to slide across the floor board due to the forces applied by the passengers of the vehicle or by the motion of the vehicle itself. One prior art solution to this problem is to apply protrusions such as nibs to the surface of the mats contacting the floor board. Typically, the nibs are formed as small spikes with pointed ends that grip the floor board surface of the vehicle. The nibs are generally equally distributed across the underlying surface to provide a number of individual contact areas. The main drawback of these flat mats is that they do not effectively cover the contoured surfaces of the floor board. Specifically, the flat mats are not effective for protecting the corners of the vehicle floor board or those areas having more complex surface shapes. Further, even those flat floor mats having nibbed surfaces tend to move along the floor board since the nibs are not in contact with the large, contoured area of the floor board and do not benefit from the lateral support afforded contoured mats.
Some prior art mats are produced to closely correspond to the shape of a vehicle floorboard and overcome the problems inherent with flat sheets. The complementary shape of the contoured mat mates with the vehicle floorboard to hold the mat into place. However, the prior art processes for producing these contoured mats have a number of shortcomings. One prior art process is the use of thermoforming to produce a multi-dimensional, contoured mat. In this process, a polymer sheet is placed over a solid molding from defining the shape of the mat. The sheet is softened by heating in an oven and is held to the form by either vacuum or air pressure forcing the sheet against a female or male tool. However, while this prior art method has been effective for forming appropriately shaped mats at a relatively low cost, the prior art thermoforming processes do not disclose a method for forming integral nibs on the mat. In some cases, manufacturers have attached a plate having a nibbed surface to the bottom of the thermoformed mat as part of a secondary operation. Typically, the plate is secured to the mat by a mechanical means or by one of a variety of adhesives. Besides requiring an additional step, the mats formed in this manner typically only have nibs on the lower, flat portion of the mat surface. The contoured portion of the mats, such as the upwardly extending sidewalls of typical floorboards are left smooth and do not grip the floor covering of the vehicle. Also, in some situations, the fixed plate may either become loose or partially separated from the contoured mat.
Some prior art processes have produced integrally formed nibs on the underside of a contoured mat. One example of such a process is injection molding. In this method, molten material is injected into the cavity and cooled to form the final part. In another process, used primarily with rubber mats, the mat is compression molded within a closed mold placed under pressure. However, these processes are particularly, if not prohibitably, costly. Accordingly, a process is needed that allows nibs to be integrally formed within a multi-dimensional, contoured mat without the costs associated with these expensive prior art techniques.